Fig. 4. Car and BMP2 synergize to upregulate Pitx2 in mesoderm. Ventral views of chicken embryos implanted with cell aggregates expressing BMP2 (A,C-E), Nodal (F,G), Car (H-K,M), and BMP2 and Car (N). Cell implants were placed in left and right LPM (A-D), left LPM (E,K,M) or right LPM (F-J,N). Embryos were cultured in New culture and subsequently subjected to whole-mount in situ hybridization with probes for Nodal (C,F,H,I,) Pitx2 (D,G,J,K,N), Cfc (A,M) or human BMP2 (E). (B,L,O) Transverse sections through the embryos shown in (A,K,N). Insets in H,I show cell implants expressing Car. Red arrowheads indicate ectopic expression as a result of the manipulation. Asterisk marks the implanted cell aggregates.